Question

Construct a cycle with the following steps:
Begin with: 1 mol ideal monatomic gas at 300 K and 1 bar. Point A.
1. Isothermal reversible expansion till volume gets twice its original value. Point B.
then, 2. Irreversible adiabatic expansion against P_ext=0.25 bar till P_ext=P_int, point C, temperature is 300K at this point.
then, 3. 0„2Isothermal reversible compression at the temperature of point C to V_D.0„2
step 4. Adiabatic reversible compression back to point A. Note, while it may seem like V_D is undefined, you can get it by considering the reverse of step 4 using the information you have about A.0„2
1. Draw a PV diagram.0„2
2. Calculate q,w,delta U, delta S for each step, as well as delta S and efficiency of the entire cycle.0„2

I did drew the graph for it but I'm not sure if that's correct because one the second step in that curve has a right angle.
Also, can you just give me the equations for all these energy calculation?